Well gravel packing apparatus



Feb. 18, 1969 J. R. SOLUM 3, 2 9.

WELL GRAVEL momma APPARATUS Filed May a. 1967 Sheet 2 of 4 INVENTCR. Q 74455 16 5010/14 BY 1 Azrazwzs Feb. 18, 1969 J. R. SOLUM WELL GRAVEL PACKING APPARATUS Filed May 8, 1967 INVENTOR.

M. w E w M J Feb. 18, 1969 Sheet Filed May a, 1967 7 MW v. w 2 4 RM 5 z w 0 a A Z 7 T4 N d w a m z z/ z W m .416 W 5 @v m m w I! A a J Y a m B Feb. 18, 1969 J. R. SOLUM WELL GRAVEL PACKING APPARATUS Sheet Filed May a. 1967 INVENTOR, J4M5 6 5040/14 Ai'fdZ/WFVE United States Patent 18 Claims ABSTRACT OF THE DISCLOSURE An apparatus for continuously packing gravel in a well at elevated pressures having a fluid pump and a pair of pressure vessels for containing and injecting the gravel into the flowing fluid with the fluid flow being alternated between the vessels for continuous operation to allow filling of the inactive vessel with gravel while injecting gravel from the other vessel. The vessels include an end portion through which the fluid flows and an internal feed mechanism for positively injecting gravel into the fluid flowing through the end portion at a predetermined rate which may be varied to produce any desired gravel-fluid ratio.

BACKGROUND OF THE INVENTION This invention relates to an apparatus for packing gravel in wells such as is done in the annulus externally of a slotted liner to inhibit the intrusion of unconsolidated sands into the liner along with the production fluid and, in particular, is directed to an apparatus for supplying fluid with entrained gravel at consistent and any predetermined gravel-to-fluid ratio at elevated pressures for accomplishing a reliable placement of the gravel in the well.

The attributes of packing gravel or other insoluble granular materials in oil and water wells for the control of various conditions such as the intrusion of unconsolidated sands and the sloughing of the formation are well known. In its very simplest form gravel packing of shallow water wells consisted merely of manually pouring gravel of a predetermined size between the liner and the well bore from the ground level. However as the depth of the well increases and difliculties in the formation are encountered, the problems of placing the gravel between the liner and the well bore increase. The gravel need only be placed at that portion of the bore from which fluids are being produced which is at a substantial depth. The conventional method for conducting the gravel to that depth is to entrain the gravel in a fluid appropriate to the well, such as water, and by continuously pumping the fluid the gravel remains in physical suspension until reaching the bottom where the fluid passes inwardly through the liner slots and the gravel is deposited. The gravel is of a controlled size larger than the liner slots and suited to the particular well condition. Normally the particle size of the gravel is of a closely controlled size within a range between 8 and 20 mesh US. Standard, which is more like coarse sand than gravel but is commonly termed gravel. insoluble granular material other than gravel may be used as circumstances require. Because of its small particle size the gravel can be successfully retained in physical suspension in the fluid for gravel packing if the fluid is kept moving at a suflicient rate and the gravel is adequately dispersed throughout the fluid without any slugs of high gravel concentration. Improper dispersion of the gravel within the fluid creates the risk of the gravel plugging or bridging across a particular location in the pipe or the down-hole tools before reaching the desired location of the gravel whereupon substantial and expensive remedial work may be required to release the plugged portion. Such bridging or plugging may even occur in the annulus between the well bore and the slotted liner whereupon an incomplete gravel fill results and the desired beneficial results of gravel packing will not be obtained.

While the obvious solution may appear to be to use high fluid velocities and very low concentrations of gravel in the fluid, this is not completely acceptable and normally is impractical. The amount of gravel required will depend on the particular well, in some oil wells may easily reach as much as 50 tons (which is about 1,000 cubic feet), and therefore it must be pumped into the well at a substantial rate to keep the entire operation within practical time limits. Moreover the conditions in the well itself will dictate certain limitations as to fluid pressures and velocities. For example, excessively high fluid pressures cannot be used which would cause an excessive input or loss of the fluid into the oil producing formation thereby adversely affecting the production of the well. Conversely a preselected level of elevated fluid pressure is usually required to maintain the well in a proper condition throughout the gravel packing operation.

Thus the apparatus for performing a proper gravel packing operation must be capable of continuously supplying fluid at a given elevated pressure with gravel evenly dispersed within the fluid and preferably at a sufficiently high gravel-fluid concentration to minimize the time required to complete the gravel packing without risking bridging or plugging of the gravel.

Heretofore the apparatus for gravel packing consisted primarily of two different styles each of which had substantial deficiencies that are overcome by this invention. One style employed a pressure vessel having a top opening for periodically introducing charges of gravel and a valved bottom opening beneath which passed the main fluid line whereby when the bottom valve was opened the gravel descended by gravity into the stream of fluid and was conducted to the well. This had the inherent deficiency of producing a nonuniform dispensing of the gravel into the fluid since gravity will necessarily cause the first. portion of gravel to be dispensed at a higher rate than the last portion trailing out of the vessel. Thus the rate of gravel dispersal from the vessel must be adjusted to produce an acceptable gravel-fluid ratio with the first portion and yet the average rate of dispersal is substantially lower whereby the rate of gravel placement is impaired. Further, it is impossible to determine precisely when the last gravel has trailed out of the vessel and therefore normal procedure is to wait an ample time thereby causing a non-productive delay. The second type of relatively conventional gravel packing apparatus may take many forms but principally relies on continuously introducing the gravel into the fluid on the suction side of the pump at zero fluid pressure whereby the uniform introduction of the gravel is greatly simplified. However the abrasive nature of the gravel produces excessive wear on the pump itself to the extent that it has been found that the pump valves must be replaced after gravel packing just three or four wells. Moreover with this type system there is always the risk that a slug of gravel will inadvertently be introduced into the pump and cause severe damage. The present invention overcomes these two basic problems of uniform controllable gravelfluid concentration and protection of the fluid pump.

SUMMARY OF THE INVENTION By this invention there is provided a gravel packing apparatus for controlled injection of gravel into flowing fluid under pressure by means of a pressure vessel for containing the gravel with means for physically feeding the gravel to a portion through which the fluid under pressure is passed from a pump to the well.

An object of this invention is to provide a novel form of gravel packing apparatus having a pair of pressure vessels adapted to be alternately filled with gravel and be mechanically dispense the gravel into a stream of pressurized fluid at any predetermined rate with one vessel being filled while the other is dispensing to produce a continuous supply of gravel containing fluid.

Another object of this invention is to provide a novel form of pressure vessel for a gravel packing apparatus comprising an elongated cylinder containing a screw conveyor in the bottom mating with a smaller cylinder for physically conveying gravel from the larger cylinder at a predetermined rate into the smaller cylinder where the gravel is injected into the flowing fluid. A still further object is to provide such a vessel extending in the horizontal direction and including a second internal screw conveyor along the upper portion for filling the main cylinder with gravel along its entire length although the gravel is introduced only at one end. Still a further object is to provide such screw conveyors with variable speed hydraulic motors for allowing infinite adjustment of the speeds of the conveyors and yet allowing stalling without damaging any components.

Another object of this invention is to provide a novel form of pressure vessel for a gravel packing apparatus including an elongated cylinder oriented horizontally with a ram movable in the cylinder to feed gravel to one end for controlled injection of the gravel into a fluid stream flowing through that end. A further object of this invention is to provide a double acting ram to alternately feed gravel toward both ends for continuous operation by refilling the cylinder behind the direction of movement of the ram from another vessel.

Still another object of this invention is to provide a pressure vessel with controlled vibration-producing means for feeding the gravel in a predetermined manner for injecting the gravel in a fluid stream.

Another object is to provide a novel gravel injecting vessel including means for continuously and sealably conveying gravel from an inlet open to atmospheric pressure to an outlet station through which pressurized fluid continuously flows.

A further object of this invention is to provide a novel gravel packing apparatus adapted for substantially automatic and continuous operation by the inclusion of two pressure vessels arranged for filling one while dispensing gravel from the other and a supply conveyor adapted to supply a predetermined amount of gravel for alternately filling each vessel.

Other and more detailed objects of the present invention will appear from the following description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAJWINGS FIGURE 1 is a plan view of the gravel packing apparatus of this invention with the upper fluid tank portion removed from clarity of illustration.

FIGURE 2 is a sectional elevation of the novel pressure vessel of this invention for injecting gravel into the fluid stream taken substantially on the line 22 in FIG- URE 1 and foreshortened by omitting intermediate portions of the length of the vessel.

FIGURE 3 is a sectional elevation of the tubular end portion of the vessel taken substantially on the line 33 in FIGURE 2. 1

FIGURE 4 is a sectional elevation of a typical section along the length of the pressure vessel taken substantially on the line 44 in FIGURE 2.

FIGURE 5 is a fragmentary sectional elevation of the means for alternately supplying gravel to the two vessels taken substantially on the line 5-5 in FIGURE 2.

FIGURE 6 is a diagrammatic illustration of the piping among the various components of the apparatus of this invention.

FIGURES 7 through 12 each diagrammatically show a modified form of pressure vessel for injecting gravel, similar in function to the vessel shown in detall in FIG- URE 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now more particularly to FIGURE 1, the apparatus of this invention is generally designated 10 and is preferably a completely self-contained unit capable of performing the desired functions at the well site without the use of any additional pumps, motors, etc. at the well site. However this completely self-contained feature is not essential to the invention as will appear from the description. The apparatus is shown and described in detail in connection with the pressure vessel illustrated in FIG- URE 2 but it will readily appear to those skilled in the art that the vessels illustrated in FIGURES 7-12 may be substituted.

The apparatus 10 is supported on a frame 11 which frame may be part of a truck or trailer frame for transporting the apparatus to the well site or completely independent for transportation in any desired fashion. The apparatus 10 conveniently includes two diesel or gasoline internal combustion engines 12 and 13 for providing the power to operate the various components of the apparatus. Fuel tanks 14 for the engines are also provided. The engine 12 provides the power to operate the main fluid pump, generally designated 15, through a transmission 16, torque converter 17 and chain drive 18 to the crank case end 19 of the pump 15. Pump 15 is preferably of the large dual or triple piston and cylinder type capable of substantial pressures at relatively substantial velocities, as for example up to 4,000 psi. and 5 barrels per minute. Positioned above the pump 15 and other components shown in FIGURE 1 is a tank assembly 20 (shown in FIGURES 2 and 6) which supplies the fluid to the suction 21 of pump 15.

The engine 13 is provided for operating a number of other components although it will readily be understood that a larger engine 12 could be provided and serve to operate such components in addition to the operation of pump 15. The output of engine 13 is connected by V-belt drives to a pair of hydraulic pumps 22 which are preferably of the variable volume delivery type and which serve to operate various hydraulic components of the apparatus 10 as will hereinafter be described. A high volume, low pressure fluid pump 23 is also driven by engine 13 through a V-belt drive and such pump is used for filling the aforementioned tanks 20 from any convenient fluid source or reservoir. A pair of air tanks 24 are included with the apparatus and filled with air from a compressor (not shown) driven by either of the engines 12 or 13. The compressed air from tanks 24 is used for operating various powered devices, such as remotely controlled valves, and for other purposes. The apparatus 10 will also include an electrical system for lights and controls operated from generators on the engines 12 and 13.

Means are provided for producing the precise and controlled introduction of gravel into the fluid stream in accordance with the objects of this invention and, as shown in the drawings, these means may include the pair of gravel injection pressure vessels, generally designated 30 and 31. The vessels 30 and 31 are identical and although one vessel can successfuly perform the gravel packing operation two vessels are highly preferred whereby one vessel serves to inject gravel into the fluid stream While the other vessel is being filled with gravel and vice versa thereby permitting a continuous supply of fluid and gravel to be delivered to the well. Since the gravel injector pressure vessels 30 and 31 are identical only vessel 30 will be described in detail by particular reference to FIGURES 2, 3 and 4. The main body of the vessel 30 is comprised of a cylinder 32 of substantial length compared to its diameter whereby it is capable of containing a substantial volume at the high fluid pressures involved without being excessively heavy. On the upper side of one end of the vessel 30 is provided a circular opening and fitting 33 having an upwardly facing flange 34. A flange 35 is removably mounted on flange 34 and has a central circular opening. A hopper 36 is mounted on flange 35 for receiving and directing gravel into the vessel 32 through the opening in flange 35. The flange 35 has a downwardly facing valve seat 37 surrounding the central opening which is adapted to mate with a conical valve plug 38 suspended within fitting 33 and below flange 35 by a rod 39. The upper end of rod 39 is connected to a powered cylinder 40 for raising the conical plug 38 into engagement with valve seat 37 to form a pressure-tight seal therebetween and for lowering the plug 38 to the position shown in FIGURE 2 for admitting gravel. Cylinder 40 is supported on a frame 41 bridging the hopper 36 and is remotely controlled for convenience.

Means are provided in the gravel injector vessel 30 for distributing the gravel introduced at one end throughout the length of the vessel and, as shown in the drawings, these means may include a small screw conveyor 42 extending the entire length of the cylinder 32 along the uppermost portion of the cylinder. The screw conveyor 42 is supported at each end by a bearing and pressure-tight stutfing box assembly 43 and intermediate its ends by a bearing 44 suspended from a hanger 45 attached to the cover 46 of an access opening in the top of the vessel. The shaft of screw conveyor 42 extends out the end of vessel 30 remote from fitting 33 and has a sheave 47 mounted thereon. A hydraulic motor 48 selectively driven by the aforedescribed hydraulic pump 22 serves to drive the conveyor 42 by the sheave 47 through a drive sheave 49 and belt 50. The vessel 30 is filled with gravel by introducing the proper amount (measured in a manner hereinafter described) of gravel through the hopper 36 with the hydraulic motor 48 operating to drive the conveyor 42 in the direction shown by arrow 51 whereby the gravel is urged in a direction from right to left as viewed in FIG- URE 2. Of course the first quantity of gravel introduced will merely fall to the bottom of the vessel 30 below fitting 33 but as additional amounts are introduced the gravel is conveyed along the vessel by conveyor 42 with the surrounding gravel serving as the conveyor housing thereby progressively moving the gravel along the vessel until the full charge is distributed along the length of the vessel. While the screw conveyor 42 is not surrounded by a metal housing whereby stalling of the conveyor might readily occur, the use of the hydraulic motor 48 is still preferred to accommodate any stalling that might occur by reason of some malfunction or inadvertent overfilling of the vessel. Fluid is introduced along with the gravel through a pipe 52 to wet the gravel which assists in distributing the gravel along the vessel with a minimum degree of abrasion and breaking of the gravel and also serves to fill the vessel with fluid before closing the valve plug 38 against seat 37. Thus it may be seen that through the use of screw conveyor 42 the entire elongated vessel 30 may be conveniently and rapidly filled with gravel in preparation for pressurizing the vessel and introducing the gravel into the fiuid for packing the well.

Means are provided within the gravel injector pressure vessel 30 for positively feeding gravel from the vessel at variable predetermined rates and, as shown in the drawings, these means may include a screw conveyor 55 extending the length of the vessel along the bottom. Each end of the screw conveyor 55 is rotatably supported by a bearing and pressure-tight stufling box 56. The right hand end of the pressure vessel 30 is provided with a cylindrical portion 57 extending outwardly (and inwardly to a limited extent) from the end of the larger cylinder 32 with the lowermost interior wall portions of the cylinders 32 and 57 aligned. The screw conveyor 55 is of a diameter to closely fit the interior diameter of the tubular end portion 57 whereby a positive feed of the gravel is achieved by the conveyor 55 within such portion 57. Along the major length of the vessel 30 the conveyor 55 is substantially smaller than the cylinder 32 and therefore does not closely fit the walls of the cylinder 32 as clearly shown in FIG- URE 4. Thus like the conveyor 42, the screw conveyor 55 throughout the major length of the vessel 30 merely serves to move the gravel along the vessel from left to right as viewed in FIGURE 2 when the conveyor is rotated in the direction of arrow 58 with the surrounding gravel serving as the conveyor housing. The conveyor 55 is driven by a hydraulic motor 59 through a belt drive 60 and gear reduction box 61 mounted on the end of portion 57. The hydraulic motor '59 is powered by the hydraulic pumps 22 and is of the variable speed type for driving the conveyor 55 at any desired speed. Within the tubular end portion 57 the screw conveyor 55 terminates at 62 spaced from the stufling box assembly 56 in the end portion 57 whereby a flow chamber 63 is formed between the end of the conveyor and the closed end of the portion 57. A pair of spaced inlet ports 64 are provided on the upper side of the chamber 63 and a large outlet port 65 is provided on the bottom of chamber 63 to form a Y- shaped flow pattern thorugh chamber 63 as shown in FIG- URE 3. In this manner the flow pattern is not obstructed by the shaft 66 of the conveyor 55 as would occur with a single inlet port diametrically positioned from the outlet port. The outlet port 65 is of substantial size relative to the diameter of the end portion 57 to minimize the possibiilty of gravel accumulating on the sides of chamber 63. Further a spiral vane 67 of a pitch reversed from that of the conveoyr 55 is provided on shaft 66 between outlet 65 and the end of portion 57 to urge any gravel reaching such vane back toward the outlet 65. Whenever the conveyor 55 is operated to move the gravel toward chamber 63 fluid is passed through chamber 63 from inlets 64 to outlet 65 whereby the gravel reaching chamber 63 is immediately injected into the moving fluid stream. The rate of gravel injection into chamber 63 by conveyor 55 is uniform and unvarying so long as the rate of rotation of conveyor 55 remains the same. The gravel-fluid concentration ratio of course will depend on the rate of fluid flow through chamber 63 as well as the rate of rotation of conveyor 55. However once those two rates are established the ratio is fixed and the full charge of gravel contained in the vessel 30 is injected and flows to the well at such ratio. Since the rate of gravel introduction into chamber 63 is uniform and the gravel is immediately dispensed into the flowing fluid, there is no opportunity for slugs of gravel to be introduced into the fluid flow as with previously conventional systems. Thus a very high gravelfluid ratio can be safely adopted which previously would have been impossible due to a likelyhood of a slug of gravel occurring in the flow of fluid. Moreover since the rate of gravel injection is mechanically controlled (by the speed of conveyor 55 as driven by motor 59) the rate of gravel injection or even the rate of fluid flow can be varied at any time even while injecting gravel from that pressure vessel to selectively change the fluid-gravel ratio. This is in contrast to previous gravity flow systems wherein once the valve was open the rate of flow and resultant ratio could not be modified or controlled.

During the injection of gravel into the fluid stream by means of the conveyor 55 the vessel 30 is pressurized to the same pressure as the fluid flowing through chamber 63 from inlets 64 to outlet 65 and of course the valve plug 38 is closed against the seat 37 at the gravel charging hopper. The fluid pressure within vessel 30 is supplied through line 68 from the pump 15 in the manner which will appear more fully hereinafter to pressurize the vessel at the same time the flow of fluid through chamber 63 is started. Thereafter as gravel is dispensed from the vessel 30, the volume of the gravel is replaced by fluid continually introduced through line 68 and the pressure is maintained. Line 68 is preferably connected at the end of vessel 30 remote from the gravel dispensing end portion 57 whereby the natural fluid and gravel flow is all from left to right, as viewed in FIGURE 2, during the gravel dispensing operation. In order to refill the vessel 30 with gravel after the flow of fluid through chamber 63 has been terminated, the fluid must be discharged from the vessel to provide space for accommodating the gravel and this is done by opening a drain line 69 which is conveniently located at the bottom of one end of the vessel. In order to accelerate the draining and avoid any problem if the fluid is drained to a reservoir at a higher level, air pressure may be supplied from tanks 24 through line 70 to force the fluid from the vessel. Upon completion of the draining, the drain line 69 and air line 70 are closed and the valve plug 38 may be opened by actuating cylinder 40 to allow filling of the vessel with gravel in the aforedescribed manner.

In the gravel packing of most wells it is essential that the amount of gravel required to pack the well be calculated and that the quantity of gravel be metered into the well until this calculated requirement is reached. In order to accomplish this metering of gravel into the gravel injector pressure vessels 30 and 31 and also to facilitate the handling of the gravel, a metering conveyor 75 is mounted on the apparatus between the two vessels 30 and 31. The conveyor 75 is of the positive metering type screw conveyor wherein the screw closely fits the cylindrical housing wall whereby a given number of revolutions will advance a predetermined quantity of gravel along the conveyor. The conveyor 75 is mounted on an incline whereby the input hopper 76 on its lower end will be at ground level for ease in loading gravel into the hopper. A hydraulic motor 77 drives the conveyor 75 through a belt drive 78 and gear reduction 79 all mounted on the upper end of the conveyor. For convenience the conveyor 75 may be slidably mounted by a dovetail plate 80 engaging a permanently mounted pedestal 81 whereby the conveyor 75 may be moved longitudinally upwardly to a position for transportation of the apparatus 10 with the hopper 76 elevated off the ground. The upper end of conveyor 75 is provided with a downwardly facing discharge opening 82 positioned above but between the hoppers 36 of the vessels 30 and 31. Referring more particularly to FIGURE 5, the deflector chute 83 is pivotally mounted below discharge opening 82 and extends laterally over the hoppers 36 of the vessels. A pneumatic or hydraulic cylinder 84 is operable to pivot the chute 83 about the horizontal axis to deflect the gravel from discharge opening 82 into either of the hoppers 36 of the vessels 30 and 31. Simi larly the fluid from line 52 is deflected by the chute 83 into either of the hoppers 36 along with the gravel. Once the conveyor 75 is full of gravel and gravel is continually supplied to hopper 76, a given number of revolutions of the screw will discharge a preselected amount of gravel from opening 82 and thence into the particular vessel 30 or 31. Thus for convenience a revolution counter 85 is provided and includes a servo mechanism for stopping the hydraulic motor 77 after a predetermined number of revolutions adjustably set on the counter 85 to thereby dispense the desired amount of gravel into one of the vessels 30 or 31. Once the deflector chute 83 has been pivoted toward the other vessel the motor 77 can be activated again and the counter 85 will again allow only the desired number of revolutions of the conveyor to fill that vessel with the proper quantity of gravel. A screen 86 is provided above the hoppers 36 of the vessels to prevent objects from being inadvertently dropped into the vessels. The controls for the operation of all of the aforedescribed components including remote control for operating the engines 12. and 13 may be centrally located at a control stand 87 positioned on a platform 88 conveniently located above the vessels 30 and 31 and adjacent the tank assembly 20 whereby the operator can observe and control the various operations.

The overall operation of the apparatus 10 of this invention may best be described by reference to FIGURE 6 where the various components are diagrammatically illustrated. The well head 90 of the particular oil or water 8 well to be gravel packed includes a string of tubing 91 suspended in the Well and extending to the location where the gravel is to be placed and a return line 92 communicating with the annular space outside the tubing 91. As is conventional the tubing 91 will have a crossover tool at the top of the slotted liner whereby the downwardly flowing fluid and gravel in tubing 91 will flow outwardly to the annular space and the returning fluid will flow from inside the liner to the annulus surrounding tubing 91 above the crossover tool and then to the return line 92, all of which is conventional. The return line 92 discharges into a reservoir 93 which may be a large tank or sump pit at the location of the well. The reservoir 93 will be filled with the particular fluid to be used in gravel packing the well which fluid will be selected on the basis of the conditions of the well and may be plain water, salt water, diesel fuel, etc. depending on the specific gravity required and the type of well. A back pressure regulating valve 94 may be provided in line 92 to maintain a certain pressure on the well if the weight of the fluid is not adequate to prevent the well from producing fluid. The fluid is taken from reservoir 93 by the aforedescribed pump 23 through a suction line 95 and supplied to the metering tank 20 by line 96 permanently installed on the apparatus 10. In order to carefully meter the fluid used in the gravel packing operation the tank 20 is divided into two sections of predetermined capacity and these are alternately filled from line 96 by opening one of the pair of valves 97 while the fluid is being taken from the other section of the tank. The suction line 98 of pump 15 is connected to the two sections of tank 20 and valves 99 are alternately opened to meter the fluid supplied to the pump. The high pressure discharge line 100 from pump 15 is connected through a valve 101 to the line 102 leading to the tubing 91 at the well head 90 whereby fluid may be supplied directly from pump 15 to the well head to maintain fluid circulation when gravel is not being supplied. The pump discharge line 100 is also connected by lines 103 and 104 to the inlets 64 of the pressure vessels 30 and 31 respectively. Inlets are diagrammatically shown as a single conduit in FIG- UR-E 6 but are in fact of the dual conduit construction shown in FIGURE 3. A pair of valves 105 and 106 are provided in each of the inlet lines 103 and 104 to the vessels 30 and 31. The aforedescribed fluid line 68 for supplying fluid to the top, remote end of the pressure vessel is connected to the respective conduits 103 and 104 between the locations of valves 105 and 106. The lines 68 may have a valve 107 but normally such valve will be continually left in the open position. Similarly, throughout normal operation the valves 106 will be left in the open position and will only be closed for the remedial operation of flushing line 68 if by some inadvertence the line 68 becomes clogged. The outlets 65 of the vessels 30 and 31 are respectively connected by conduits 108 and 109 to the line 102 leading to the well head and each outlet has a valve 110 associated therewith. Thus with valves 106 and 107 normally open the flow of fluid from pump 15 may be directed through the end portions 57 of either the vessels 30 or 31 by closing valve 101 and opening the respective valves 105 and 110 associated with that vessel. In turn this will supply pressurized fluid through the respective line 68 to replace with fluid the volume of gravel discharged from the vessel. As soon as all of the gravel has been dispensed from one vessel, for example vessel 31, the valves 105 and 110 associated with that vessel are closed and the valves 105 and 110 associated with the other vessel 30 are simultaneously open to maintain a continuous supply of gravel and fluid to the well head 90. A valve 111 in the air line 70 leading to vessel 31 is then opened to exert an air pressure on the vessel and a valve 112 in the drain line 69 from vessel 31 is opened to conduct the fluid from vessel 31 to the reservoir 93. When vessel 31 is empty valves 111 and 112 are closed, the gravel inlet valve plug 38 is opened, the discharge chute 83 is pivoted toward the hopper 36 of vessel 31,

valve 113 in the fluid line 52 is opened and the conveyor 75 is actuated whereby the vessel 31 is then refilled with gravel and fluid in the aforedescribed manner. [During this refilling of vessel 31, the vessel 30 is dispensing its charge of gravel and vessel 31 will be refilled before vessel 30 has completed such dispensing whereby the positions of the respective valves 105 and 110 may be simultaneously switched to then dispense the gravel from vessel 31 while 30 is being refilled. When the desired quantity of gravel has been dispensed toward the well head 90 the fluid supply can be continued uninterrupted by merely closing both valves 105 and both valves 110 and simultaneously opening valve 101 to supply the fluid from pump directly to the well head.

Referring now to FIGURE 7 an alternate form of gravel injection pressure vessel 150 is diagrammatically shown which may be substituted in the apparatus 10 for one or both of the aforedescribed vessels and 31. Vessel 150 comprises an elongated cylinder having a gravel inlet opening 151 on the top of one end which may be opened and closed by conical plug 152 similar to the aforedescribed plug 38. A small screw conveyor 153 extends the length of the vessel for distributing the gravel therealong during filling similar to conveyor 42. A piston or ram 154 fits the interior of the vessel and is adapted to be urged the length of the vessel by a powered cylinder 155. Ram 154 has an opening 156 therein to accommodate conveyor 153. After filling vessel 150 with gravel the ram 154 serves to urge the gravel at a preselected rate toward the other end 157 which is provided with the diametrically spaced fluid inlet 158 and outlet 159 similar to aforedescribed inlet 64 and outlet 65 to inject the gravel into the flowing fluid at any predetermined rate. The ram 152 serves the gravel feeding function of conveyor 55 of the preferred embodiment but is slightly less positive.

Referring now to FIGURE 8, another alternate form of gravel injection vessel 170 is shown. The vessel 170 has a gravel inlet opening 171 and valve plug 172 for introducing gravel into the vessel. The vessel has an end portion 173 with a valve 174 and adjustable orifice mechanism 175 mounted therein and fluid inlet 176 and outlet 17'7 therethro-ugh for the passage of the main flow of pressurized fluid through such end portion. The vessel is mounted for vibrating movement and vibrating means 178 are provided. By operating the vibrating means 178 in a selected manner the gravel can be urged in either direction within the vessel. Thus during gravel filling the means 178 are operated to move the gravel from right-toleft and for dispensing gravel the means 178 move the gravel from left-to-right as viewed in FIGURE 8. By coordinating the size of the orifice in end portion 173 by mechanism 175 and the fed-producing vibration produced by means 178, the rate of gravel injection into the flowing fluid is controlled as thoroughly as by the mechanical positive fed of the aforedescribed devices.

Referring now to FIGURE 9, still another gravel injection pressure vessel 190 is shown. Here the vessel may be mounted on an incline with the gravel fill opening 191 and closure plug 192 at the upper end. At the lower end is provided a star wheel feed mechanism 193 adapted to be driven at any desired rate to positively feed the gravel into the fluid stream passing through end portion 194 therebelow. A valve 195 is provided immediately below feed mechanism 193 for closing during filling of the vessel with gravel.

Referring now to FIGURE 10, another form of gravel injection vessel 200 may conveniently be spherical and has a top inlet opening 201 for admitting gravel and which is controlled by a closure plug 202. The bottom of the vessel opens into a horizontal cylinder 203 containing a screw conveyor 204 for feeding the gravel to an end portion 205 through which the fluid flows from inlet 206 to outlet 207. The screw conveyor 204 can be driven at any speed to produce the desired fluid-gravel ratio.

FIGURE 11 illustrates still another form of gravel injection pressure vessel 210 again having a gravel inlet 211 and closure plug 212. A horizontal cylinder 213 extends in both directions from the bottom of the vessel and a piston 214 is movable therein by actuator 215. Each end of cylinder 213 is connected to conduit 216 and 217 controlled by inlet valve 218 and leading to a common outlet conduit and valve 219. By reciprocating the piston 214 in cylinder 213 the gravel is alternately delivered to conduits 216 and 217 at the desired rate and by appropriately alternating the positions of oppositely positioned valves 218 the fluid flow will be through the conduit into which the gravel is being injected.

The gravel injection pressure vessel of FIGURE 12 comprises a cylinder 230 open at both ends with a disc type conveyor 231 passing therethrough. A gravel inlet 233 having a normally open valve 234 is used for the continuous introduction of the gravel into the cylinder. Spaced along the cylinder are a diametrically located inlet 235 and outlet 236 through which the pressurized fluid flows and which may also be provided with valves. The discs 232 of conveyor 231 form a pressure tight seal with the cylinder and the cylinder length and disc spacing is such as to always provide the necessary pressure seals between the fluid inlet-outlet location and the ends of the cylinder as well as the location of the gravel inlet 233. Thus a continuous feed is accomplished thereby avoiding the necessity for two vessels on the apparatus.

Each of the vessels shown in FIGURES 7-12 are diagrammatically illustrated and may also be provided with accessory elements such as the fluid line 68, drain line 69 and air line 70 as required with the particular arrangement.

It may be seen by the apparatus of this invention a precisely controlled ratio of gravel-to-fluid may be continuously supplied at elevated pressures to a well for gravel packing and this ratio may be relatively high since there is no substantial variation in the rate of gravel dispensing throughout the dispensing cycle from the gravel injection vessels, regardless of which of the forms of vessels is employed. While the invention has been described in connection with a number of particular embodiments it is to be understood that the invention is not limited to the details set forth in the specification or the details shown in the drawings but rather the invention is of the full scope of the appended claims.

I claim:

1. An apparatus for packing insoluble material in wells with a supply of fluid at elevated pressure, comprising, a pair of pressure vessels each having a valve-controlled opening for alternately introducing a predetermined quantity of the material into each vessel, each vessel having a flow-through portion connected into the supply of pressurized fluid flowing to the well, valve means for selectively and alternately supplying the fluid through said portion of either vessel, means in each said vessel for affirmatively feeding the material into said flow-through portion of that vessel at a predetermined rate for injecting the material into the flowing fluid, and alternately introducing the material into one vessel through said opening while injecting the material in the other vessel into the fluid flowing to the well.

2. The apparatus of claim 1 wherein a selectively operable feed con veyor includes adjustable means for selectively metering a predetermined quantity of the material into the said valve-controlled opening of either of the vessels.

3. An apparatus for continuous gravel packing of wells at elevated pressures, comprising, a fluid pump for continuously providing fluid under pressure, conduit and valve means for selectively connecting said pump directly to the well as required for supplying fluid without gravel to the well, a pair of pressure vessels each having a tubular end portion with substantially diametrically located inlet and outlet, conduits connecting said fluid pump to the said inlets and having valve means for selectively supplying fluid from the pump to either vessel, conduits connecting said outlets to the well and having valve means for selectively connecting the well to the outlet of the vessel to which fluid is being supplied for passing fluid through that said tubular end portion, a fluid supply line connected to each said vessel at a location remote from said end portion for supplying fluid to the vessel while fluid is supplied through the end portion of that vessel, each said vessel having a charging opening controlled by valve means for selectively introducing gravel into that said vessel while fluid is being supplied through said end portion of the other vessel, a conveyor means in each said vessel selectively operable while fluid is flowing through the end portion of that vessel and having means for positively feeding the gravel in the vessel into said tubular end portion at a predetermined rate for injecting the gravel into the fluid flowing through said end portion to produce a predetermined gravel-fluid ratio, means for varying the operation of said conveyor means to vary said predetermined rate of gravel injection and in turn vary the gravel-fluid ratio, means for selectively supplying air under pressure to each said vessel while all the fluid supply is interrupted to that vessel for exhausting the fluid from that vessel for allowing refilling with gravel, and a supply conveyor having means for metering a predetermined quantity of gravel into either vessel through said charging opening with the said controlling valve means open.

4. An apparatus for gravel packing of wells with circulating liquid supplied at elevated pressures, comprising, a pressure vessel having a tubular end portion extending therefrom with substantially diametrically located inlet and outlet, conduit means connecting the liquid supply to said inlet and connecting said outlet to the well, said vessel having a charging opening controlled by valve means for selectively introducing gravel into said vessel while liquid is not being supplied through said end portion of the vessel, a mechanical conveyor means in said vessel extending into said end portion but not forming an obstruction between said liquid inlet and outlet, said conveyor means selectively operable while liquid is flowing through the end portion of the vessel and having means for preventing the free flow of gravel into said end portion and positively feeding the gravel present in the vessel into said tubular end portion at a predetermined rate for injecting the gravel into the liquid flowing through said end portion to produce a predetermined gravel-liquid ratio, and means for varying the speed of operation of said conveyor means to vary said predetermined rate of gravel injection and in turn vary the gravel-liquid ratio.

5. The apparatus of claim 4 wherein said vessel is an elongated cylinder oriented horizontally, and said conveyor means comprises a screw conveyor of a diameter smaller than said cylinder and extending along the bottom of the cylinder for the full length of the cylinder.

6. The apparatus of claim 5 wherein a second and smaller screw conveyor extends along the top of the cylinder for the full length for spreading the gravel throughout the length of the vessel from the location of said charging opening.

7. An apparatus for packing insoluble material in wells with a supply of pressurized flowing liquid, comprising, a pressure vessel having a valve-controlled opening for introducing the material into the vessel, said vessel having a liquid flow-through portion with an inlet and an outlet in spaced relation for the supply of pressurized liquid to flow through said portion from said inlet to said outlet, and means in said vessel for delivering the material introduced at said opening to said liquid flowt'hrough portion in a controlled manner for injection into said flowing liquid, said means including a mechanical conveyor means extending to said liquid flow-through portion for physically metering said material into said portion and having means cooperating with the vessel for preventing the free passage of material from within the vessel to said portion without the operation of said conveyor means.

8. The apparatus of claim 7 wherein said vessel has said valve-controlled opening near one end for introducing material, and mechanical means for transferring the material along the length of the vessel for substantially filling the vessel.

9. The apparatus of claim 7 wherein said pressure vessel is comprised of an open ended cylinder with said conveyor means comprising a continuous conveyor passing through the cylinder and having sealing means for allowing pressurizing of said cylinder.

10. The apparatus of claim 9 wherein said cylinder has a portion for introducing the material and a spaced portion comprising said flow-through portion with said feeding means continuously moving from the first said portion to the flow-through portion, and said conveyor means sealing between said first portion and said flow-through portion of the cylinder.

11. The apparatus of claim 9 wherein said conveyor is comprised of spaced discs sealably engaging the cylinder and movable along the cylinder.

12. The apparatus of claim 7 wherein a metering conveyor is provided for introducing a predetermined amount of material into said valve-controlled opening, and said metering conveyor has adjustable means for selecting said predetermined amount of material.

13. The apparatus of claim 7 wherein said vessel is an elongated cylinder and said mechanical conveyor means comprises a screw conveyor of a diameter smaller than said cylinder and extending the full length along the bottom of the cylinder with said liquid flow-through portion at one end of said screw conveyor.

14. The apparatus of claim 13 wherein said vessel is provided with a smaller diameter cylinder extending from one end and mating with said screw conveyor, said smaller diameter cylinder providing said liquid flow-through portion and the said mating with the screw conveyor providing the said preventing of free passage of material into said portion.

15. The apparatus of claim 13 wherein said screw conveyor has a vane thereon positioned in said flow-through portidn beyond the location of said inlet and said outlet for urging any material passing beyond said inlet and outlet back toward said inlet and outlet and into said flowing liquid.

16. The apparatus of claim 7 wherein two said pressure vessels are provided for permitting continuous packing of the insoluble material in a well, valve means provided on the said inlet and said outlet of each said vessel for alternately supplying the pressurized flowing liquid to one or the other vessel, and means for alternately feeding the insoluble material through the respective valve-controlled opening to the vessel while the said valve means are positioned for not supplying the flowing liquid to that vessel.

17. The apparatus of claim 16 wherein the said feeding means includes a metering conveyor having automatic shut-off means for supplying any preselected amount of said material to the said vessel.

18. The apparatus of claim 14 wherein said valve-controlled opening is at the same end of said vessel as the location of said smaller diameter cylinder, and said smaller diameter cylinder extends inwardly into the said vessel for a relatively short distance for further preventing the direct passage of the material from the said valvecontrolled opening to said flow-through portion of the vessel without operation of said conveyor means.

(References on following page) References Cited UNITED STATES PATENTS Fleckenstein 2222-35 XR Davis 222-235 XR Jones et a1. 222238 Redler 222-136 XR Roberts 22'257 XR Ridley 222241 14 2,594,687 4/1952 Scott 222-238 2,800,252 7/1957 Wahl 222233 XR 2,872,166 2/1959 Roberts '22'2r-136XR WALTER SOBIN, Primary Examiner.

US. Cl. X.R. 

